telltale

[noah4009]

I read the above post on telltales. Still I am confused. Can I add a telltale to my Chrysler 1971 55HP motor. On the top of the head is a post. with a wire attached. I looked at my parts manual and it says this is a thermostat switch with the thermostat wire. The wire is orange and runs to the board of wires that says orange-heat. On the above post on telltales it says drill a hole in head or remove some type of bolt from top of head. Can you please explain how I do this to add a telltale.

 

[john from md]

Re: telltale

First, you need a manual if you don't have one. Next, you need to find the area where your thermostat is housed. On the thermostat housing, there is usually a 3/8" plug. It can have a slotted head, like a common screw or have a square head like a plug in a house water or gas line.

You can remove this plug and, adding components found in Homedepot, make a telltale.

You are correct about the wire and terminal on your engine's head. This is for overheat alert only and has nothing to do with mounting a telltale. You should check to see that this works however by shorting the wire to ground with the power on. This should produce a alarm buzz from under the dash showing that at least your overheat wiring works.

Regards,

John

 

[noah4009]

Re: telltale

First, you need a manual if you don't have one. Next, you need to find the area where your thermostat is housed. On the thermostat housing, there is usually a 3/8" plug. It can have a slotted head, like a common screw or have a square head like a plug in a house water or gas line.

You can remove this plug and, adding components found in Homedepot, make a telltale.

You are correct about the wire and terminal on your engine's head. This is for overheat alert only and has nothing to do with mounting a telltale. You should check to see that this works however by shorting the wire to ground with the power on. This should produce a alarm buzz from under the dash showing that at least your overheat wiring works.

Regards,

John

I do have all my manuals to this motor. There is nothing on the housing of the thermostat. The only thing coming from this housing is a plug with a water line attached. The thermostat is located on the top front part of the plate that covers the head. On the head there is a plug and on this plug is attached the thermostat wire. This wire runs from the terminal that is orange for heat. That is the only plug on the head. Are you saying for me to remove the plug that has the waterline attached. That feeds water to the thermostat? If so, do I get a plug with two outlets one for the hose and one for the telltale?

 

[Frank Acampora]

Re: telltale

On the older 55s, the overheat indicator was on the surface of the head. It was a 5/8 head X 1/4 screw that replaced one of the bolts holding the head cover on. Glued to the 5/8 head was a slug of "plastic" with a wire terminal coming out of it. It sounds to me like you have a temperature sender screwed into the top of the head. If it is brass, about an inch and a half tall, with an approximately 1/2 inch hex on it, with a terminal coming out of the top center, it is very likely it is a temperature sender for a gauge. If you unscrew it and it has a brass slug about 1/2 inch long in the bottom, it is definitely a temperature sender. If you do not intend to use it, you could replace it with a small barbed fitting for a pisser. This hole is almost always threaded 1/8 NPT--unless someone dicked it up and re-threaded it.

However, there should be enough meat on the block directly behind the thermostat to drill and tap 1/8 NPT for a fitting--not sure if flywheel ring gear would interfere though. If your engine still has a clear hose running from the block to the thermostat, why not just put a TEE in that hose?

Quite frankly, I don't understand the fuss about indicators. I never see a need for a pisser and never install one on any of my engines. Just because Merc has one doesn't mean it is an absolute necessity. Personally, I would rather look forward at a gauge in the dash than backward for a stream of water. Believe me, if water flow stops and temperature starts to rise, the engine will not be damaged if you are looking at a temp gauge and take action.

 

[noah4009]

Re: telltale

Thanks Frank
I will do as you say and get a gauge.

 

[Frank Acampora]

Re: telltale

The gauge will also come with a sending unit. Remove what is in your head and use the one that comes with the gauge. Wiring is orange wire from sender to orange terminal on engine terminal board. Orange wire in cable to orange terminal on engine terminal board. Other end of orange wire to one side of gauge. Power from "I" terminal on ignition switch to other side of gauge. Use a length of red wire, 16-18 gauge (diameter) from the "I" terminal to the temp gauge to avoid confusion. Red is typically power and black is typically ground on boats. Don't worry, Instructions are included and show connections.

With the ignition switch on, "I" terminal delivers 12 volt potential to the gauge. As the "sender" heats up, it's resistance to ground (automatically grounded through the head) decreases and allows more voltage to flow through the gauge to ground. Thus the hotter it gets, the higher the gauge reads. With the ignition switch off, no voltage is delivered to the gauge and it reads 0 or minimum temperature on the gauge.

You will need to monitor the gauge under normal running to see exactly what temperature is normal for your engine. It may be 160, 180, or even a bit higher. The time to worry is if the gauge shows over 200.

 

[arsenalpsu]

Re: telltale

I wouldn't waste any money for a telltale on this motor, or a gauge. You can see the water spitting out of the back of the engine. I have a 55hp with a new impeller and housing, it spits fare enough out of the exhaust to see if from the drivers seat when turning.